Moving a wire across a magnetic field causes electrical current to flow in the wire. You might remember demonstrations in school science classes. That’s how generators work - by moving wires past magnets.
You can amplify the effect by having a bundle of wires. Which is why generators have coils of wires.
But it doesn’t have to be physical movement. All you really need is a magnetic field that fluctuates over time. So if you have a coil of wires next to an electromagnet, and that electromagnet is fed by an electricity source that changes over time, that induces current in the coil.
Remember how in the old days you could charge your iPhone in the microwave? Well, now you can do it on your cooktop. (Known as ERCIFBERM, or Extremely Rapid Charging Immediately Followed By Extremely Rapid Melting.)
Is an electromagnet necessary? I was thinking just two coils of wire separated by an air (or dielectric) gap. One coil is fed AC, which induces a voltage in the other coil. Works well if there’s good coupling (coils close together, etc.).
I’ve had this question, too. And I may need a general how a battery works refresher.
Do I understand it correctly that (new) electrons are not coming FROM the charger. The electrons are being moved/re-positioned within the battery by (the field induced by) the charger?
That’s correct, shunpiker. Even a wired charger won’t move very many new electrons into a device, and it moves the same amount out, and all electrons are identical anyway, so it doesn’t matter.
It should also be noted, by the way, that the energy transfer in wireless charging only works at very small ranges (i.e., significantly shorter than the sizes of the two coils). So it’s fine for a phone sitting in a cradle, but wouldn’t work even for a phone up against your ear or in your pocket, and certainly not for a phone you’re carrying around the city.
Yeah, but when we start beaming power from our earth orbiting solar power station we might be able to keep our phones charged while carrying them around the city.
And we won’t need coats because we’ll all be nice and toasty.
Now that all this foolishness about magnets and induced electrical currents is done for… remember guys, this is GQ, not MPSIMS! The real answer is obviously MAGIC. I can’t believe you all believe this hooey about induction
Is there an easy, at-home way to test if a non-phone induction charger is working? The battery in my car key fob keeps dying. It’s supposed to be charged by induction from something in the steering wheel column when the car is running. I’m not sure if the induction charger isn’t working or if the part in the key that charges the battery isn’t working. Since a new key costs $200, I’m hoping I can figure out if the charger still works. Is there anything I can put near the steering column to know if the induction charger is working?
Some people are unaware that basically the power to your home goes through a number of “cordless” connections.
Every transformer is “cordless” in that a coil creates a magnetic field which is picked up by a second coil and converted to electrical current. (OK EEs, we will ignore the occasional auto-transformer).
So at the power plant the system goes current/magnetic field/current through one or more step up transformers.
Then the power travels through transmission lines.
It does another current/magnetic field/current at the distribution substation
Then the power travels through distribution lines.
It does another current/magnetic field/current at the pad-mount or pole-mount transformer near your home.
It does this because the voltage level is optimized for the situation. Lower voltage for generation, higher voltage for transmission, lower voltage for distribution and low voltage for usage.
example
Generator output voltage 22,000 volts
step-up transformer 22,000 in 161,000 out
distribution station 161,000 in 12,000 out
pad-mount or pole-mount 12,000 in and 250 out.
I don’t know how to tell for sure, but this link (talking about BMWs, dunno if that’s your vehicle) talks about ways to charge the fob, including driving while it’s inserted into the ignition, and using a regular wireless charging pad.
Anyway - if you have a wireless pad, you could try putting the fob on that for a bit. Is there any kind of indicator on the fob showing that it’s currently charging? If it behaves better when you try that, that might be an indicator that it’s the car’s charging system. That’s probably more money to fix than the fob would be, but at least then you could get by with using a cheap charging pad instead.
Does your fob plug in anywhere, or just dangle near the steering column? If so, is there a chance it needs to be in juuuuust the right position for charging to work? Could you try holding your phone against whatever surface, to see if the phone thinks it’s charging? (unlikely to be successful; when I tried a wireless pad for mine the thing had to be in EXACTLY the right spot or nothing happened).
Thanks a lot for the link. My car is indeed a BMW. The key is a single unit with regular metallic part that fits into the ignition with the fob part as the head of the key. Since the key is in the ignition switch itself, it should be properly aligned. Unfortunately, there’s no charging indicator light or anything on the key. Fortunately, I do have a wireless charging pad for my phone, so I’ll see if that helps at all.
Are you saying your fob has a real, key-like stick of metal coming out of it? Or is it like the graphic in Mama Zappa’s link, where the whole fob just kind of sits in the slot in the dash? Do you have Comfort Access, meaning you don’t have to stick the fob into the slot to start the car? If you have Comfort Access, the battery in the fob is not rechargeable.
